A liquid crystal display (LCD) has been widely applied to such electronic products with a display function as mobile phones, computers, TV and the like. It is well known that the LCD needs a backlight to perform display. Characterized by being small in volume, low in power consumption, long in service life, wide in color gamut and the like a light emitting diode (LED) has become the main source of the LCD backlight source. However, since the LED has such inherent disadvantages as being small in light emitting angle, bad in uniformity and the like, the backlight source formed by LED has such problems in use as uneven display brightness and the like.